Rather than disallowing the default account to be renamed as was
proposed in #245 (and implemented in #246), the default account name
is no longer considered a reserved name by the address manager.
Instead, it is simply the initial name used for the first initial
account.
A database upgrade removes any additional aliases for the default
account in the database. This prevents a lookup for some name which
is not an account name from mapping to the default account
unexpectedly (potentially preventing incorrect account usage from the
RPC server due to bad iteraction with default parameters).
All unset account names in a JSON-RPC request are expected to be set
nil by btcjson. This behavior depends on btcsuite/btcd#399.
Additionally, the manager no longer considers the wildcard * to be a
reserved account name. Due to poor API decisions, the RPC server
overloads the meaning of account fields to optionally allow referring
to all accounts at a time, or a single account. This is not a address
manager responsibility, though, as a future cleaner API should not use
multiple differet meanings for the same field across multiple
requests. Therefore, don't burden down future APIs with this quirk
and prevent incorrect wildcard usage from the RPC server.
Closes#245.
ec6034e2d9